stats (version 3.6.2)

# replications: Number of Replications of Terms

## Description

Returns a vector or a list of the number of replicates for each term in the formula.

## Usage

`replications(formula, data = NULL, na.action)`

## Arguments

formula

a formula or a terms object or a data frame.

data

a data frame used to find the objects in `formula`.

na.action

function for handling missing values. Defaults to a `na.action` attribute of `data`, then a setting of the option `na.action`, or `na.fail` if that is not set.

## Value

A vector or list with one entry for each term in the formula giving the number(s) of replications for each level. If all levels are balanced (have the same number of replications) the result is a vector, otherwise it is a list with a component for each terms, as a vector, matrix or array as required.

A test for balance is `!is.list(replications(formula,data))`.

## Details

If `formula` is a data frame and `data` is missing, `formula` is used for `data` with the formula `~ .`.

Any character vectors in the formula are coerced to factors.

## References

Chambers, J. M., Freeny, A and Heiberger, R. M. (1992) Analysis of variance; designed experiments. Chapter 5 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.

`model.tables`

## Examples

Run this code
``````# NOT RUN {
## From Venables and Ripley (2002) p.165.
N <- c(0,1,0,1,1,1,0,0,0,1,1,0,1,1,0,0,1,0,1,0,1,1,0,0)
P <- c(1,1,0,0,0,1,0,1,1,1,0,0,0,1,0,1,1,0,0,1,0,1,1,0)
K <- c(1,0,0,1,0,1,1,0,0,1,0,1,0,1,1,0,0,0,1,1,1,0,1,0)
yield <- c(49.5,62.8,46.8,57.0,59.8,58.5,55.5,56.0,62.8,55.8,69.5,
55.0, 62.0,48.8,45.5,44.2,52.0,51.5,49.8,48.8,57.2,59.0,53.2,56.0)

npk <- data.frame(block = gl(6,4), N = factor(N), P = factor(P),
K = factor(K), yield = yield)
replications(~ . - yield, npk)
# }
``````

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